Process of producing refractory calcareous sandstones.



Patented May 24, 1904.

Tl UNITED. STATES [PATENT OFFICE.

WILHEnM SQHWARZ, OF ZURICH, SWITZERLANDLASSIGNOR, BY ,MESNE ASSIGNMENTS, TO SOHWARZ' SYSTEM BRICK COMPANY, A OORPORA- TION OF NEW YORK."

'TPRQCESSQOFIIPROVDUCIEJG R-EFRACTOFtY 'oA c REoussnubs-rouse.

' srEcmIcA'IrIoN f rming aito'r Letters Patent No. 7 0,571, dated m 24, 1904. w a r Application filed February 19, 1903.

1 b, all whom may concerns I.

Be it known that I, ILHEL ScHWAnz, a c t zen of theRepublicof Switzerland,and a resident of Zurich, in-the canton Zurich and Bepublicof switzerlandghave invented acertainxnew and useful Process of Producing Refractory CalcareousSandstones, of which the following. is a full, clear, and exact specification." H

This invention relates to the manufacture of'calcareous sandstones; and its object is to render practicable theproduction of calcareous sandstones. which shall: be capableof effect ually resisting the action of all 'acidsi'and likewise the action of extremelyhigh degrees of heat, such qualityof heat and acid resist ance being characterized by the term refrac-' tory as applied'i n' metallurgy.

The'invntion consists in anovel mode of procedure wherebythe attainment of the foregoing objects is rendered feasible, which mode of procedure willnow be described and there'- after concisely set forth in the appended The resistance to heat of the calcareous sandstones made in the usual manner has hith erto been about equal to that ofwell-burnt clay bricks; but whether by steam-hardening or electrolytic hardening anabsolute resistance to'heat in the sense of the word refrac tory in metallurgy has never been attained in such calcareous sandstones.

The'present invention relates to a process whereby a calcareous sandstone is 'made which is refractory to both heat and acids and may be used for the purpose to which Dinas bricks, porcelain clay, and magnesia bricks are now applied. The process does not involve the addition of any chemical agent to the raw materials or the I treatment of the finished stone with chemical preparations or solutions.

The reason why the ordinary artificial cal- Seria1No.14 1,13 1i :(No specimens-l: I l

said refractoriness is because they are made from quartz-sand wlthoutregard to the mineralogical composition thereof. Grains or crystals of quartz, however, frequently con- 'tate against absolute refractoriness'of the cal V careous sandstone.

careoussandstones-do not possessthe afore- I When forthe. purpose of counteracting the effect of foreign substances or 'elementsin'the quartz-crystals the formed objectlis heated to a temperature near that at which quartz melts, the increase of' volume produced by the change 10f the quartzfrorn the crystalline to the amorphous state deforms the objectfand thisindeed frequently occurs inthe sintering or other refractory stones manufactured fr-cm quartz "and plastic binding materials if the mass be sharply heated after it has been fashioned.

In order to manufacture highly-refractory calcareous sandstone without involving a special chemical treatment and without distortion of the shape of the formed object, the follow ing process isadopted according to this invention. 7

The quartz-sand with which is to be combined limeoran analogous product, slaked or I unslaked, is first freed from all extraneous ele-' mentssuch as other minerals, organic sub stances,- water, liquid carbonic acid, iron combinations, and salts by subjecting such quartz-sand separately to a high degree of heat, any approved apparatus or medium, including current electricity, if essential, being availed of for such purpose; but the degree of heat employed should not equal that required to melt the quartz.-

To generate incandescent heat, current electricity is apparently most suitable, as there exists in the Voltaic are a reducing atmosphere which not only prevents the formation of silicate of iron, but insures a volatilization of the iron combinations of the quartz.

It is known that amorphous silica reacts more quickly and easily on basic substances than crystalline-quartz silica does. If, therefore, a sandsubjected to this preliminary treatment is to be mixed with lime, it is necessary, if the raw material is to be rationally prepared, to add only the minimum proportion of lime to obtain in the presence of water an extremely active reaction with the silicic acid,

and in consequencea very plastic mixture.

The objects formed from such mixture when they shall have been hardened, Whether electrolyticallyor by the aid of steam under pressure, as commonly practiced, possessa high quality of refractoriness by virtue of the small quantity of lime or analogous product comprised therein, the substantial volume of silicic acid present therein, and the absencetherefrom of extraneous elements, such as frequently accompanies quartz-sand under natural conditions.

For themanufacture of the herein-described Having thus described my invention, What I claim, and desire to secure by Letters Patent, is

1. The process of manufacturing refractory calcareous sandstones, which consists in first heating granulated quartz nearly to its melting-point, combining the same with lime, and then forming the combined lime and quartz into suitable shapes, substantially as described.

2. The process of manufacturing refractory, calcareous sandstone, which consists in first heating quartz-sand nearly to the meltingpoint to drive out impurities contained in the quartz-grains, combining the said pure quartz with lime, to form a plastic mass and molding the mass under pressure into the objects desired, substantially as described.

3. The process of manufacturing refractory, calcareous sandstone which consists in first heating quartz-sand by means of current electricity to a degree nearly sufficient to melt the quartz, combining the said. purified sand with lime, and then forming the combined lime and quartz-sand into suitable shapes, substantially as described.

VVILHELM SCH WARZ.

Witnesses v H. WETTSTEIN, A. LIEBERKNEGI-IT. 

